The storage and distribution of hydrogen can be effected in different ways. For example, hydrogen can be stored in compressed form in suitable high-pressure tanks which allow storage at up to a pressure of 875 bar. Further, storage of the liquefied low-temperature hydrogen in suitable cryogenic containers, preferably in superinsulated cryogenic containers is known. The last named possibility is implemented in particular with hydrogen-powered vehicles-independently of whether they are powered by means of a modified combustion engine or by means of a fuel cell which drives an electric motor.
Storage systems are in the experimental stage in which the storage of the hydrogen takes place in organic compounds capable of hydrogenation which are able to chemically bind the hydrogen. Such storage systems are known under the designations MPH (methylcyclohexane poluene hydrogen), decaline/napthalene and n-heptane/toluene system.
Common to the aforementioned systems is that the hydrogen is brought to reaction with them under suitable conditions so that hydrogenation and storage of the hydrogen results.
All the aforementioned alternatives have specific advantages and disadvantages so that the decision in favor of one of the alternatives is usually determined by the specific applications and circumstances. The fundamental disadvantage of the last-named alternative until now has been that the chemical reaction systems used have relatively high vapor pressures, are thus volatile and contaminate the hydrogen to a considerable degree.
To achieve high degrees of purity for the hydrogen in particular, such reaction systems must, therefore, be removed, often at great expense in terms of technology and/or energy.
The person skilled in the art is continuously striving to create a storage potential for hydrogen which allows storage of the hydrogen in a pure or absolutely pure form, where storage should be possible in the safest and most economical manner possible. Hydrogen is needed in a very pure form particularly in the operation of fuel cells. In the case of the modified combustion engines mentioned as well, which usually have a downstream catalytic converter, storage of the hydrogen in (ultra)pure form is striven for since otherwise the hydrocarbons entrained with the hydrogen (may) have a negative effect on the activity and life of the catalytic converter. Particularly in the use of hydrogen in the so-called mobile applications-operation of vehicles, etc.—the safety aspect is paramount; this applies especially for the refueling process which is usually performed by the driver himself and therefore by a “technical layman.”
Thus, there may be a need for an alternative method of storing hydrogen, which method may be efficient and/or secure.